Traumatic diaphragmatic hernia (TDH) is generally a consequence of thoraco-abdominal trauma. Anaesthetic problems arise due to herniation of abdominal contents into the thoracic cavity causing diaphragmatic dysfunction, lung collapse, mediastinal shift and haemodynamic instability. Diagnosis depends on history, clinical signs and radiological investigations. Sometimes, it may be misdiagnosed as hydropneumothorax due to the presence of air and fluid in the viscera lying in the pleural cavity. We report a case of TDH mimicking hydropneumothorax on radiological investigations and subsequent surgical management, which led to serious complications.